WILLIAM E. RYAN
Associate Professor
ECE Dept., University of Arizona, Box 210104, Tucson, AZ 85721
ph: (520) 621-8690   e-mail: ryan@ece.arizona.edu

EDUCATION

          Ph.D. (E.E.), University of Virginia, May 1988.  

            Dissertation: "Two Classes of Convolutional Codes over GF(q) with
            Applications  to Frequency-Hopping Channels."  (Advisor: Stephen Wilson)

            Minors: Pure math and control theory.

          M.S.E.E., University of Virginia, August 1984.

            Thesis: "Generalized Cross-Correlation Performance with Spectrum Signals."

          B.S.E.E., Case Western Reserve University, January 1981.  

   
EXPERIENCE        

Assoc. Professor, University of Arizona, August 1998 - Present

Research

        Coding and modulation for bandwidth-limited communication channels

        Signal processing and coding for magnetic recording

        Equalization and compensation for nonlinear channels

Courses Taught (at UA and at NMSU)

        Signals and Systems (undergraduate course)

        Intro to Communications (undergraduate course)

        Random Signals

        Digital Communication Systems I

        Digital Communication Systems II

        Channel Coding

        Detection and Estimation Theory

Research Funding

        NASA (1993-present)

        Loral WDL (1995)

        Sandia National Laboratories (1994)

        National Science Foundation (1994-present)

        National Storage Industry Consortium (1998-present)

        Intel (2003)

Technical Contributor to CCSDS Panel 1A Meetings on Turbo Code Standards

Assistant Professor, New Mexico State University, August 1993 - August 1997.

Engineer III, Applied Signal Technology, February 1993 - August 1993.

Responsibilities included first simulating adaptive beam forming (gradient search) algorithms for the rejection of interfering signals and then implementing the algorithms in Motorola 68040 firmware.

Co-designer of the error detection and correction (EDAC) system employed in the DST-600 recorder, a high density, high reliability (error rates less than 10-13) supercomputer/mainframe data storage peripheral.

Wrote full simulation program (in C) for the EDAC system for both hardware verification and performance analysis.    

Designed high rate (11/12 and 17/18) DC-free recording codes for use with Viterbi-detected Class IV partial response channels.    

Wrote Viterbi detector simulation programs to produce test vectors for a new high speed Viterbi chip and to evaluate the reliability of erasure flags produced via decoder metrics. 

Specified partial response equalizer for Miller-squared encoded channels and designed its optimal (Viterbi) detector. Off-tape experiments have shown this detector to improve error rates by a factor of 50.

Member Technical Staff, The Analytic Sciences Corp., January 1988 - August 1990.  
Responsibilities included performing studies on various topics (some classified) within the areas of signal processing, communications, and coding.

Was Co-Principal Investigator for a research project on trellis coding for magnetic recording channels and another on cyclostationary signal processing techniques.

Provided system-level designs for upgrading an errors-only Reed-Solomon (RS) decoder to an errors-and-erasures decoder and for a universal  RS decoder.

Devised a performance analysis technique for evaluating the performance of erasure decoding of interleaved RS codes on burst error channels.    

Studied the effects of A/D and D/A clock jitter on SNR.

Fairchild Fellow, American Satellite Co. / University of Maryland, May 1984 August 1985.

Fairchild Fellowship Program. Tasks included C band and Ku band link analyses and software development for testing and monitoring earth stations.  Completed 12 credit hours of graduate course work at the University of Maryland.

Associate Engineer, General Dynamics, Convair Division,  February 1981 - August 1982.  

Tasks included the design and implementation of a digital angular position controller and supervision of production testing of avionics hardware.

Cadet, U. S. Coast Guard Academy,  June 1976 - December 1977.  

Various Summer Positions: (1) University of Virginia, 1987. Instructor for course on signals and linear systems. (2) M/A COM Government Systems, 1986. Estimation-theoretic analyses on accuracy limitations of satellite position location and antenna pointing in a low-orbiting multiple satellite system. (3) Harris Corporation, 1983. Simulation program of remotely piloted vehicles communicating in the presence of jammers and a study of pseudo-noise sequence acquisition for direct-sequence spread-spectrum signals.

Invited Book Chapters

W. E. Ryan, "An Introduction to LDPC Codes," in CRC Handbook for Coding and Signal Processing for Recording Systems (B. Vasic, ed.) CRC Press, to be published in 2004.

W. E. Ryan, "Concatenated Codes and Iterative Decoding," in Wiley Encyclopedia of Telecommunications (J. G. Proakis, ed.) New York:Wiley and Sons, 2003.

Journals

M. Yang, W. E. Ryan, and F. Peng, "Simple LDPC code design techniques for correlated fading channels," in preparation for submission to the IEEE Trans. Veh. Tech.   

B. Xia and W. E. Ryan, "Importance sampling for LDPC codes," in preparation for submission to the IEEE Trans. Comm.

Y. Li, M. Yang, W. E. Ryan, M. Duvivier, and B. Shah, "Rate-compatible LDPC codes for large internet file multicast," in preparation for submission to IEEE Trans. Broadcasting.

W. E. Ryan and Z. Tang, "Reduced-complexity error state diagrams in TCM and ISI channel performance evaluation," accepted, IEEE Trans. Comm., 2002.  

M. Yang, W. E. Ryan, and Y. Li, "Design of efficiently encodable moderate-length high-rate irregular LDPC codes," IEEE Trans. Comm., Vol. 52, No. 4, pp. 564-571, April 2004.  

M. Yang and W. E. Ryan, "Performance of efficiently encodable LDPC codes in noise bursts on the EPR4 channel," IEEE Trans. Magnetics, Vol. 40, No. 2, pp. 507-512, March 2004.   

A. Muqattash, M. Krunz, and W. E. Ryan, "Solving the Near-Far Problem in CDMA-Based Ad Hoc Networks," Elsevier Ad Hoc Networks Journal, Vol. 1, No.  4, pp. 435-453, November 2003.  

S. Yang, A. Kavcic, and W. E. Ryan, "Optimizing the Bit Aspect Ratio of a Recording System Using an Information-Theoretic Criterion," IEEE Trans. Magnetics, Vol. 39, pp. 2228-2230, Sept. 2003.  

A. L. Perez and W. E. Ryan, "Iterative detection and decoding on nonlinear ISI channels,"  IEEE Trans. Comm., Vol. 25, No. 1, pp. 1501-1505, April 2002. 

A. Ghrayeb and W. Ryan, "Concatenated code system design for storage channels," IEEE J. Selected Areas in Comm., Vol. 19, pp. 709-718, April 2001. 

R. Ramamurthy and W. Ryan, "Convolutional Double Accumulate Codes (or Double Turbo DPSK," IEEE Comm. Letters, Vol. 5, pp. 157-159, April 2001. 

W. Ryan, "Concatenated codes for class IV partial response channels," IEEE Trans. Comm., Vol. 49, pp. 445-454, March 2001.

W. Ryan, "Optimal code rates for concatenated codes on a PR4-equalized magnetic recording channel," IEEE Trans. Magnetics, Vol. 36, pp. 4044-4049, Nov. 2000.

W. Ryan, A. Ghrayeb, and N. Yeh, "Performance of random-access-memory-based equalizers in magnetic recording," IEEE Trans. Magnetics, Vol. 36, pp. 4028-4035, Nov. 2000.

A. Gutierrez and W. Ryan, "Performance of Volterra and MLSD Receivers for Nonlinear Bandlimited Satellite Systems," IEEE Trans. Comm., Vol. 48, pp. 1171-1177, July 2000. 

O. Acikel and W. E. Ryan, "Punctured turbo codes for BPSK/QPSK channels," IEEE Trans. Comm., Vol. 47, pp. 1315-1323, Sept. 1999.

W. Ryan, Li Han, and P. Quintana, "Design of a low-orbit to geostationary satellite link for maximal throughput," IEEE Trans. Comm., Vol. 45, pp. 988-996, August 1997. 

W. Ryan and B. Zafer, "A study of class I partial response signaling for magnetic recording," IEEE Trans. Magnetics, Vol. 33, pp. 4543-4550, Nov. 1997.

W. Ryan, "Optimal signaling for meteor burst channels," IEEE Trans. Comm., Vol. 45, pp. 489-496, May 1997.  

W. Ryan and N. Yeh, "MLSD detector for PR4-equalized magnetic recording channels with transition-shift and partial-erasure nonlinearities," IEEE Trans. Magnetics, Vol. 32, pp. 3950-3952, Sept. 1996.  

W. E. Ryan and A. Gutierrez, "Performance of adaptive Volterra equalizers on nonlinear magnetic recording channels," IEEE Trans. Magnetics, Vol. 31, pp. 3054-3056, Nov. 1995. 

W. E. Ryan and P. Conoval, "A method of analysis for interleaved Reed-Solomon coding with erasure decoding on burst-error channels," IEEE Trans. Comm., Vol. 41, pp. 430-434, March 1993. 

W. E. Ryan, "Comparative performance between drop-out detection and Viterbi reliability metric erasure flagging," IEEE Trans. Magnetics, Vol. 28, pp. 2898-2900, Sept. 1992. 

W. E. Ryan and S. G. Wilson, "Two classes of convolutional codes over GF(q) for q-ary orthogonal signaling," IEEE Trans. Comm., Vol. 39, pp. 30-40, Jan. 1991.  

W. E. Ryan, "Comments on 'Orthogonal convolutional coding for the PPM optical channel'," IEEE J. Lightwave Tech., Vol. 8, pp. 1007, June 1990.

Conferences

Z. Tang and W. E. Ryan, "Achievable information rates and the coding-spreading tradeoff in synchronous CDMA systems," 2003 IEEE Global Telecommunications Conference, Vol. 4, pp. 1877-1881, December 2003.

W. E. Ryan, "Optimal code rates for Lorentzian channel models," 2003 IEEE Global Telecommunications Conference, Vol.  6 , pp. 3386-3391,  December 2003. 

Y. Li and W. E. Ryan, "Design of LDPC-coded modulation schemes," to appear, Proc. 3rd Int.Symp. on Turbo Codes and Related Topics (Sept. 2003).  

M. Yang and W. E. Ryan, "Lowering the error-rate floors of moderate-length high-rate irregular LDPC codes," Proc. 2003 Int. Symp. on Information Theory, 237 pp., Yokohama, Japan, July 2003.  

B. Xia and W. E. Ryan, "Importance sampling for loop-free decoding trees with application to low-density parity-check codes," Proc. 2003 Int. Symp. on Information Theory, 120 pp., Yokohama, Japan, July 2003. 

B. Xia and W. E. Ryan, "On importance sampling for linear block codes," Proc. 2003 IEEE International Conference on Communications, Vol. 4, pp. 2904 -2908, May 2003. 

M. Yang, Y. Li, and W. E. Ryan, "Design of efficiently encodable moderate-length high-rate irregular LDPC codes," Proc. 41st Allerton Conf., Oct. 2002.  

M. Yang and W. E. Ryan, "Design of LDPC codes for two-state fading channel models," The 5th International Symposium on Wireless Personal Multimedia Communications, Vol. 3, pp. 986 -990, Oct. 2002.  

K. L. Virga, C. L. Hammond, D. Beauvarlet, and W. E. Ryan, "Indoor propagation measurements using low profile and directional dual exponentially tapered slot antennas," The 5th International Symposium on Wireless Personal Multimedia Communications, Vol. 1, pp. 193-197, Oct. 2002. 

B. Xia and W. E. Ryan, "Near-optimal convolutionally coded asynchronous CDMA with iterative multiuser detection/decoding," Proc. 2002 IEEE International Conference on Communications, Vol. 3, pp. 1521 -1525, April/May 2002.  

A. L. Perez and W. E. Ryan, "Iterative detection and decoding on nonlinear ISI channels," Proc. 2002 IEEE International Conference on Communications, Vol. 3, pp. 1501 -1505, April/May 2002.  

B. Xia and W. E. Ryan, "Near-optimal convolutionally coded synchronous CDMA with iterative multiuser detection/decoding," Proc. 2001 Global Telecommunications Conference, Vol. 2, pp. 767 -771, Nov. 2001.  

M. Yang and W. E. Ryan, "Performance of (quasi-)cyclic LDPC codes in noise bursts on the EPR4 channel," Proc. 2001 Global Telecommunications Conference, Vol. 5, pp. 2961 -2965, Nov. 2001.  

R. Ramamurthy and W. E. Ryan, "Convolutional double accumulate codes (or double turbo DPSK)," Proc. 2000 IEEE Global Telecommunications Conference, Vol. 2, pp. 795 -800, Nov/Dec 2000.  

A. Ghrayeb and W. E. Ryan, "Precoder design for concatenating convolutional codes with generalized partial response channels," Proc. 2000 IEEE Global Telecommunications Conference, Vol. 3, pp. 1859 -1864, Nov/Dec 2000.  

W. Ryan and A. Ghrayeb, "Precoder design for concatenating convolutional codes with intersymbol interference channels," Proc. 2000 Wireless Communications and Networking Conference, Vol. 3, pp. 1013 -1018, Sept. 2000. (invited)  

W. Ryan, S. McLaughlin, K. Anim-Appiah, M. Yang, "Turbo, LDPC, and RLL codes in magnetic recording," Proc. 2nd Int. Symp. on Turbo Codes and Related Topics, Sept. 2000.  

A. Ghrayeb and W. Ryan, "Concatenated coding and iterative SOVA decoding with PR4 signaling," Proc. 2000 IEEE International Conference on Comm., Vol. 2, pp. 597 -601, June 2000.  

O. Acikel and W. Ryan, "Punctured high rate SCCCs for BPSK/QPSK channels," Proc. 2000 IEEE International Conference on Comm., Vol. 1, pp. 434-439, June 2000.  

D. Goeckel, W. Ryan, and P. Ormeci, "On iterative adaptive signaling for wideband wireless channels," SPIE's 14th Annual Int. Symp. on Aerospace/Defense Sensing, Simulations, and Controls (Proc. of SPIE 4045, May 2000). (invited)  

W. Ryan, "Design considerations for concatenating convolutional codes with partial response channels," Proc. 37th Allerton Conf., pp. 1324-1333, Sept. 1999. (invited)  

A. Ghrayeb and W. Ryan, "Performance of high rate turbo codes employing the soft-output Viterbi algorithm (SOVA)," 1999 Conference Record of the Thirty-Third Asilomar Conference on Signals, Systems, and Computers, Vol., 2, pp. 1665-1669, Oct. 1999. 

W. Ryan, J. LeBlanc, and R. Kennedy, "Performance study of RAM-based decision feedback equalizers with application to nonlinear satellite channels," Proceedings of the Fifth International Symposium on Signal Processing and Its Applications, Vol. 1, pp. 407-410, Aug. 1999, Brisbane, Australia.  

W. Ryan, "Optimal code rates for concatenated codes on a PR4-equalized channel," 1999 Conf. on Inf. Sciences and Systems.  

A. Ghrayeb and W. Ryan, "RAM-Search algorithms for nonlinear ISI cancellation in magnetic recording," Proc. GlobeCom, Vol. 6, pp. 3368-3373, Nov. 1998.  

J. LeBlanc, R. Kennedy, and W. Ryan, "Pre-cursor extended RAM-DFE canceller (PERC) nonlinear equalizer for nonlinear ISI channels," The Eighth Digital Signal Processing Workshop, Bryce Canyon, Utah, Aug. 1998.  

W. Ryan, L. McPheters, and S. McLaughlin, "Combined turbo coding and turbo equalization for PR4-equalized Lorentzian channels," 1998 Conf. on Inf. Sciences and Systems.  

O. Acikel and W. Ryan, "High rate turbo codes for BPSK/QPSK channels," Proc.1998 Int. Conf. on Comm. Vol. 1, pp. 422-427, June 1998.  

W. Ryan, "Performance of high rate turbo codes on a PR4-equalized magnetic recording channel," Proc. 1998 Int. Conf. on Comm. Vol. 2, pp. 947-951, June 1988.  

B. Zafer and W. Ryan, "Performance Comparison of Selected DC-Free Codes for PR1-Equalized Magnetic Recording Channels," Proc. 1997 Int. Conf. on Comm., Vol. 3, pp. 1638-1643, June 1997.  

O. Acikel and W. Ryan, "Lossless compression of telemetry data," Int. Conf.Telemetry, San Diego, Oct. 1996.  

A. Gutierrez and W. Ryan, "The performance of MLSD receivers on nonlinear satellite channels," Proc. 1996 Int. Conf. on Comm., Vol. 2, pp. 921-925, June 1996.  

W. Ryan and B. Zafer, "Performance comparison between PR1 and PR4 signaling on high-density magnetic recording channels," Proc. 1996 Int. Conf. on Comm., Vol. 1, pp. 587-591, June 1996.  

A. Gutierrez and W. E. Ryan, "Performance of adaptive Volterra equalizers on nonlinear satellite channels," Proc. 1995 Int. Conf. on Comm.Vol., 1, pp. 488-492, June 1995.  

P. Quintana and W. E. Ryan, "Optimal parameters for a low orbit to geostationary satellite link," Proc. 1995 Int. Conf. on Comm., Vol. 3, pp. 1870-1874, June 1995.  

W. E. Ryan and Li Han, "Modulation and Coding for Short-Duration Deterministically Time-Varying Channels," Proc. 1995 Int. Conf. on Comm., Vol. 3, pp. 1790-1794, June 1995.  

W. E. Ryan, "Comparative performance between drop-out detection and Viterbi reliability metric erasure flagging," IEEE Magnetics Conference, Digests of Intermag'92, International, pp. 325-325, April 1992.  

W. E. Ryan and S. G. Wilson, "Convolutional Coding over GF(q) with Application to Frequency-Hopping Channels," MILCOM 1987 Conf. Rec.  

W. E. Ryan and S. G. Wilson, "Convolutional Coding over GF(q) with Application to Frequency-Hopping Channels," Proc. 1987 Conf. Inf. Sys. and Sci.

W. E. Ryan and J. M. Schumpert, "Time Delay Estimation for Spread Spectrum Signals Using Generalized Cross Correlation," Proc. 1985 ICASSP., Vol. 10, pp. 168-171, April 1985. 

TECHNICAL REPORTS IN INDUSTRY 

W. E. Ryan, "Limitations on Satellite Direction Finding via Power Measurements with Known Receive Antenna Pattern," M/A COM Government Systems Tech. Rep. August 1986, 20 pp.

W. E. Ryan, "Limitations on Satellite Position Determination via Range Measurements to Earth Terminals of Known Position," M/A COM Government Systems Tech. Rep., August 1986, 32 pp.

W. E. Ryan, "The Effect of A/D and D/A Clock Jitter on NPR," TASC Tech. Rep., October 1989, 25 pp.

W. E. Ryan, "The Effect of A/D and D/A Clock Jitter and Frequency Offset on the Reconstructed Signal," TASC Tech. Rep., October 1989, 14 pp.

W. E. Ryan and E. R. Muly, "Cyclostationary Signal Analysis Techniques Study, TASC Tech. Rep., November 1989, 101 pp.

P. Conoval and W. E. Ryan, "The Reduction of Overhead in the ARP Recorder Format via Advanced Signal Processing and Coding," TASC Tech. Rep., January 1990, 87 pp.

W. E. Ryan, "On Errors-Only and Errors-and-Erasures Decoding of Reed-Solomon Codes," TASC Tech. Rep., April 1990, 29 pp.

W. E. Ryan, "Upgrading Weldon's Decoder to Correct Erasures," TASC Tech. Rep., April 1990, 32 pp.

W. E. Ryan, "Design and Analysis of the MacAnalyst Frame Format," TASC Tech. Rep., May 1990, 34 pp.

W. E. Ryan, "Coding Over the AWGN Channel," TASC Tech. Rep., June 1990, 18 pp.

W. E. Ryan, "On ARQ Error Control Schemes," TASC Tech. Rep., August 1990, 11 pp.

W. E. Ryan and B. K. Lum, "Multi-Level Trellis Codes for Recording Channels," TASC Tech. Rep., August 1990, 104 pp.

W. E. Ryan, "R-90 ECC Performance Study Final Report," Ampex Tech. Rep., April 1991, 93 pp.

W. E. Ryan, "A Low-Overhead DC-Free Code for Use with Class IV Partial Response Magnetic Recorders," Ampex Tech. Memo, Mar. 10, 1992, 7 pp.

W. E. Ryan, "Theory and Design of a Viterbi Detector for Class II Partial Response-Equalized Miller-Squared Signals," Ampex Tech. Memo, Jan. 1993, 47 pp.